Aqueous dispersion including two different block copolymers

ABSTRACT

The aqueous dispersion of the present invention is produced by incorporating a block copolymer (II) into an aqueous dispersion (I) of a block copolymer (I) in an aqueous solution containing a basic compound. The block copolymer (I) is composed of a polymer block (A) mainly constituted by a constitutional unit derived from an olefin monomer and a polymer block (B) constituted by a constitutional unit derived from a vinyl monomer (b1) having a carboxyl group, a carboxylic anhydride group or a sulfonic group and a constitutional unit derived from another vinyl monomer (b2) copolymerizable with the vinyl monomer (b1). The content of the basic component is 0.05 equiv or more of the carboxyl group, carboxylic anhydride group or sulfonic group, each contained in the unit derived from the vinyl monomer (b1). The block copolymer (II) is composed of a polymer block (X) mainly constituted by a constitutional unit derived from an aromatic vinyl monomer and a polymer block (Y) constituted by a constitutional unit derived from a conjugated diene monomer. The aqueous dispersion provides a flexible coating film which is excellent in bonding and adhesion properties to various substrates.

TECHNICAL FIELD

The present invention relates to aqueous dispersions, and moreparticularly to aqueous dispersions containing at least two differentkinds of block copolymers, which are improved in the bonding andadhesion properties to various substrates.

BACKGROUND ART

Polyolefin resins such as polypropylene have been widely used asplastics for home appliances and automobile parts because of their lowcosts and excellent resin properties such as processability, waterresistance and oil resistance. To enhance their additional values, acoating layer is formed on the surface of polyolefin molded articles, orpolyolefin and another resin are made into laminates. However, sincepolyolefin has a low polarity, the adhesion of general paints or otherresins to polyolefin is poor.

To solve this problem, it has been hitherto attempted to increase thesurface polarity of polyolefin molded articles so as to improve theadhesion to paints or other resins by treating the surface in advancewith chromic acid, fire flame, corona discharge, plasma, solvent, etc.However, these treatments have problems of needing complicatedprocedures and being dangerous because of the use of a large amount ofcorrosive chemicals.

Under these circumstances, there has been proposed a method in which thesurface of polyolefin molded articles is coated with a primer mainlymade of a chlorinated polyolefin. However, since the chlorinatedpolyolefin should be dissolved in an aromatic organic solvent harmful tohuman body, such as toluene and xylene, the method causes safety andenvironmental problems. To solve the problems, there has been proposed amethod to make the chlorinated polyolefin water-dispersible (JP1-256556A and JP 4-218548A). However, this method also fails tocompletely eliminate the use of the aromatic organic solvents, and theobtained coating film is poor in weatherability and water resistance.Moreover, it has been demanded to develop an aqueous dispersion adhesivefree from chlorine in view of preventing the generation of hydrogenchloride gas upon waste incineration and a good recycling capability.

DISCLOSURE OF THE INVENTION

The inventors had made extensive study on aqueous dispersions whichprovided coating films excellent in the bonding and adhesion propertiesto various substrates, storage stability, water resistance,weatherability, etc. As a result, the inventors had found an aqueousdispersion meeting the above requirements, which was an aqueousdispersion of a block copolymer in an aqueous solution of a basiccompound, wherein the block copolymer is composed of a polymer block (A)mainly constituted by a constitutional unit derived from olefin monomerand a polymer block (B) constituted by from 2 to 100 mol % of aconstitutional unit derived from a vinyl monomer having a carboxyl groupor a carboxylic anhydride group and from 98 to 0 mol % of aconstitutional unit derived from another vinyl monomer copolymerizablewith the above vinyl monomer, and wherein the content of the basiccompound is 0.05 equiv or more of the carboxyl group or carboxylicanhydride group, each contained in the unit derived from the vinylmonomer. On the basis of this finding, the inventors filed a patentapplication (U.S. Pat. No. 6,451,901).

Thus, an object of the present invention is to further improve theproperties of the above aqueous dispersion and to provide an aqueousdispersion capable of forming a flexible coating film which is excellentin the bonding and adhesion properties to various substrates.

The inventors filed a patent application on an aqueous dispersion whichwas prepared by blending the aqueous dispersion of U.S. Pat. No.6,451,901 with at least one component selected from the group consistingof (i) a polyurethane resin, (ii) an acrylic aqueous emulsion adhesive,a vinyl acetate aqueous emulsion adhesive, a styrene aqueous emulsionadhesive, or an aqueous dispersion or an aqueous solution of a vinylpolymer such as polyvinyl alcohol, and (iii) a tackifier such assaturated petroleum resins (EP 1172407A). The inventors further filed apatent application on an aqueous dispersion which was prepared byblending the aqueous dispersion of U.S. Pat. No. 6,451,901 with (iv) acompound (curing agent) having in one molecule two or more functionalgroups, such as epoxy group, oxazoline group, carbodiimide group andisocyanate group, which were reactive with carboxyl group (JP2002-80685A). The bonding and adhesion properties to various substratesof the aqueous dispersion of U.S. Pat. No. 6,451,901 were improved bythese aqueous dispersions.

The inventors have further continued the study of the improvement in theproperties of the aqueous dispersion of U.S. Pat. No. 6,451,901. As aresult, it has been found that the flexibility of a coating film formedfrom an aqueous dispersion is improved without adversely affecting thebonding and adhesion properties to various substrates by adding acomponent other than the components (i) to (iv) to the aqueousdispersion. After further examination based on this finding, the presentinvention has been accomplished.

Thus, the present invention provides an aqueous dispersion which isproduced by incorporating a block copolymer (II) into an aqueousdispersion (I) of a block copolymer (I) in an aqueous solutioncontaining a basic compound, wherein the block copolymer (I) is composedof a polymer block (A) mainly constituted by a constitutional unitderived from an olefin monomer and a polymer block (B) constituted by aconstitutional unit derived from a vinyl monomer having a carboxylgroup, a carboxylic anhydride group or a sulfonic group and aconstitutional unit derived from another vinyl monomer copolymerizablewith the vinyl monomer; wherein a content of the basic compound is 0.05equiv or more of the carboxyl group, carboxylic anhydride group orsulfonic group, each contained in the unit derived from the vinylmonomer; and wherein the block copolymer (II) is composed of a polymerblock (X) mainly constituted by a constitutional unit derived from anaromatic vinyl monomer and a polymer block (Y) constituted by aconstitutional unit derived from a conjugated diene monomer.

PREFERRED EMBODIMENTS FOR CARRYING OUT THE INVENTION

The block copolymer (I) is composed of the polymer block (A) and thepolymer block (B) each described below. The block copolymer (I) mayinclude, for example, AB diblock copolymers, ABA triblock copolymers,and BAB triblock copolymers, with AB block copolymers being preferred.

The polymer block (A) is mainly constituted by a constitutional unitderived from an olefin monomer. The content of the olefin monomer unitin the polymer block (A) is preferably from 50 to 100 mol %, morepreferably from 70 to 100 mol % and still more preferably from 80 to 100mol % and most preferably 100 mol % based on the total molar number ofthe constitutional units of the polymer block (A).

Examples of the constitutional unit derived from the olefin monomerinclude units derived from ethylene; α-olefins such as propylene,1-butene, 2-methyl-1-butene, 3-methyl-1-butene, 1-pentene,4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene and 1-octadecene;2-butene; isobutylene; conjugated dienes such as butadiene and isoprene;vinylcyclohexane; cyclopentadiene; and β-pinene. The polymer block (A)may contain one or more kinds of these units. The polymer block (A)preferably contains a constitutional unit derived from ethylene orpropylene. More preferred blocks are a polymer block constituted by aconstitutional unit derived from propylene; a copolymer blockconstituted by a constitutional unit derived from propylene and aconstitutional unit derived from ethylene; a copolymer block constitutedby a constitutional unit derived from propylene and a constitutionalunit derived from α-olefin other than propylene; a polymer blockconstituted by a constitutional unit derived from ethylene; and acopolymer block constituted by a constitutional unit derived fromethylene and a constitutional unit derived from α-olefin other thanpropylene. If the olefin monomer unit is derived from a conjugated dienesuch as butadiene, isoprene and cyclopentadiene, the remainingunsaturated bond may be hydrogenated.

The polymer block (A) may optionally contain a constitutional unitderived from a vinyl monomer copolymerizable with the olefin monomer inan amount of from 0 to 50 mol %, preferably from 0 to 30 mol % and morepreferably from 0 to 20 mol %. Examples of the vinyl monomercopolymerizable with the olefin monomer include (meth)acrylonitrile;vinyl esters such as vinyl acetate and vinyl pivalate; (meth)acrylicesters such as methyl(meth)acrylate, ethyl(meth)acrylate,butyl(meth)acrylate, dodecyl(meth)acrylate and2-ethylhexyl(meth)acrylate; (meth)acrylamide; and N-vinyl-2-pyrrolidone.These monomers may be used alone or in combination of two or more.Preferred are methyl acrylate, ethyl acrylate and acrylonitrile.

The polymer block (B) contains a constitutional unit derived from thevinyl monomer (b1) having a carboxyl group, a carboxylic anhydride groupor a sulfonic group in an amount of from 2 to 100 mol % based on thetotal molar number of the constitutional units of the polymer block (B).To enhance the water resistance of the coating films formed from theaqueous dispersion, the content of the constitutional unit derived fromthe vinyl monomer (b1) is preferably from 2 to 45 mol % and morepreferably from 2 to 30 mol % based on the total molar number of theconstitutional units of the polymer block (B).

Examples of the vinyl monomer (b1) having a carboxyl group includeacrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconicacid and maleic acid. These may be used alone or in combination of twoor more. Preferred are acrylic acid and methacrylic acid. The carboxylgroup may be in the salt form of metal such as sodium and potassium.

Examples of the vinyl monomer (b1) having a carboxylic anhydride group(—CO—O—CO—) include maleic anhydride, itaconic anhydride, citraconicanhydride, butenyl succinic anhydride and tetrahydrophthalic anhydride.These may be used alone or in combination of two or more. Preferred ismaleic anhydride.

Examples of the vinyl monomer (b1) having a sulfonic group include4-styrenesulfonic acid, 2-methyl-2-propene-1-sulfonic acid,allylsulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid. Thesemay be used alone or in combination of two or more. The sulfonic groupmay be in the salt form of metal such as sodium and potassium.

The polymer block (B) may contain a constitutional unit derived fromanother vinyl monomer (b2) copolymerizable with the vinyl monomer (b1)in an amount of from 0 to 98 mol %, preferably from 55 to 98 mol % andmore preferably from 70 to 98 mol % based on the total molar number ofthe constitutional units of the polymer block (B).

Examples of the vinyl monomer (b2) include styrenic monomers such asstyrene, 4-methylstyrene and vinylnaphthalene; (meth)acrylonitrile;vinyl esters such as vinyl acetate and vinyl pivalate; (meth)acrylicesters such as methyl(meth)acrylate, ethyl(meth)acrylate,butyl(meth)acrylate, dodecyl (meth)acrylate, 2-ethylhexyl(meth)acrylate,tetrahydrofurfuryl(meth)acrylate andtetrahydropyran-2-methyl(meth)acrylate; (meth)acrylamide; andN-vinyl-2-pyrrolidone. These may be used alone or in combination of twoor more. Preferred are methyl(meth)acrylate, ethyl(meth)acrylate,tetrahydrofurfuryl (meth)acrylate, styrene and acrylonitrile.

The number-average molecular weight of the polymer block (A) ispreferably from 500 to 100,000 and more preferably from 1,000 to 20,000.The number-average molecular weight of the polymer block (B) ispreferably from 500 to 100,000 and more preferably from 1,000 to 20,000.The number-average molecular weight of the block copolymer (I) ispreferably from 1,000 to 200,000 and more preferably from 2,000 to40,000.

The number-average molecular weight referred to herein was determined bya gel permeation chromatography (GPC) using a standard polystyrenecalibration curve.

The weight ratio of the polymer block (A) to the polymer block (B) inthe block copolymer (I) (polymer block (A)/polymer block (B)) ispreferably from 4/1 to 1/4 and more preferably from 2/1 to 1/2.

The block copolymer (I) is produced, for example, byradical-polymerizing the monomer component for constituting the polymerblock (B) in the presence of a mercapto-terminated polymer having astructure corresponding to that of the polymer block (A). By such amethod, the block copolymer (I) having a desired number-averagemolecular weight and a desired molecular weight distribution is easilyand efficiently produced.

The mercapto-terminated polymer having a structure corresponding to thatof the polymer block (A) is produced by various methods, for example, bya method where an addition product of a double bond-terminated olefinpolymer with thio-S-acetic acid, thio-S-benzoic acid, thio-S-propionicacid, thio-S-butyric acid or thio-S-valeric acid is treated with an acidor alkali, or a method where a polyolefin is produced by anionicpolymerization using ethylene sulfide as a polymerization terminator.

If an olefin polymer is added in an amount of from 1 to 200 parts byweight per 100 parts by weight of the block copolymer (I), the strengthof the coating film formed from the resultant aqueous dispersion isenhanced in some cases. In view of the balance between the storagestability of the aqueous dispersion and the strength of the coatingfilm, the amount of the olefin polymer to be added is preferably from 1to 100 parts by weight and more preferably 1 to 50 parts by weight per100 parts by weight of the block copolymer (I). If the addition amountof the olefin polymer exceeds 200 parts by weight, the average particlesize of dispersed particles becomes large to reduce the storagestability of the resultant aqueous dispersion.

Examples of the olefin polymer include low-density polyethylenes,medium-density polyethylenes, high-density polyethylenes, verylow-density polyethylenes, linear low-density polyethylenes,polypropylene, ethylene-vinyl acetate copolymers, ethylene-ethylacrylate copolymers, ethylene-methyl acrylate copolymers,propylene-α-olefin copolymers, ethylene-α-olefin copolymers andethylene-propylene-diene (or triene) tercopolymers. These may be usedalone or in combination of two or more. Examples of the α-olefin for theethylene-α-olefin copolymers include propylene, 1-butene, 1-pentene,1-hexene, 4-methyl-1-pentene, 1-octene and 1-decene. Examples of thediene or triene for the ethylene-propylene-diene (or triene)tercopolymers include aliphatic non-conjugated dienes such as1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene,6-methyl-1,6-heptadiene and 7-methyl-1,6-octadiene; alicyclicnon-conjugated dienes such as cyclohexadiene, dicyclopentadiene,methyltetrahydroindene, 5-vinylnorbornene, 5-ethylidene-2-norbornene,5-methylene-2-norbornene, 5-isopropylidene-2-norbornene and6-chloromethyl-5-isopropenyl-2-norbornene; and trienes such as2,3-diisopropylidene-5-norbornene,2-ethylidene-3-isopropylidene-5-norbornene,2-propenyl-2,5-norbornadiene, 1,3,7-octatriene and 1,4,9-decatriene.These olefin polymers may be modified by known methods, for example, bya halogenation such as chlorination and bromination; chlorosulfonation;epoxidation; hydroxylation; anhydrous carboxylation; and carboxylation.

The aqueous dispersion (I) can be produced by dispersing the blockcopolymer (I) and the optional olefin polymer into an aqueous solutioncontaining a basic compound in an amount of 0.05 equiv or more of thecarboxyl group, carboxylic anhydride group or sulfonic group of thepolymer block (B) at a temperature not lower than the melting point ofthe block copolymer (I). If the optional olefin polymer is used, thedispersion is preferably conducted at a temperature not lower than thehigher melting point of the block copolymer (I) and the optional olefinpolymer. If dispersed at a temperature lower than the higher meltingpoint, the average particle size of dispersed particles becomes large tolower the stability of the aqueous dispersion (I).

The dispersion may be performed using a pressure container equipped witha stirring means. Preferred examples of stirring means include, but notlimited to, turbine-type stirrer, colloid mill, homomixer, andhomogenizer, because a large shear force is obtained. Alternatively, thedispersion may be performed using a line mixer equipped with a movablestirrer or a line mixer equipped with a non-movable stirrer such as“Static Mixer” (tradename of Noritake Co., Ltd.).

Examples of the basic compound include ammonia; amine compounds such ashydroxylamine, hydrazine, hydrazine hydrate, methylamine, ethylamine,propylamine, butylamine, hexylamine, octylamine, ethanolamine,propanolamine, dimethylamine, diethylamine, dipropylamine, dibutylamine,dihexylamine, dioctylamine, diethanolamine, dipropanolamine,trimethylamine, triethylamine, tripropylamine, tributylamine,trihexylamine, trioctylamine, triethanolamine, tripropanolamine,N-methyldiethanolamine, N,N-dimethylethanolamine,N,N-diethylethanolamine, 2-dimethylamino-2-methyl-1-propanol,2-amino-2-methyl-1-propanol and cyclohexylamine; quaternary ammoniumsalts such as tetramethylammonium hydroxide and tetrabutylammoniumhydroxide; metal oxides such as sodium oxide, potassium oxide, calciumoxide, strontium oxide and barium oxide; metal hydroxides such as bariumhydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide andstrontium hydroxide; carbonates such as sodium carbonate, potassiumcarbonate, sodium hydrogencarbonate, potassium hydrogencarbonate andcalcium hydrogencarbonate; and acetic acid salts such as sodium acetate,potassium acetate and calcium acetate, with ammonia, methylamine,ethylamine, propylamine, butylamine, dimethylamine, diethylamine,dipropylamine, dibutylamine, N-methyldiethanolamine, triethylamine,N,N-dimethylethanolamine, N,N-diethylethanolamine,2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, sodiumhydroxide and potassium hydroxide being preferred, and ammonia, sodiumhydroxide and potassium hydroxide being more preferred, in view of easyavailability and the stability of the aqueous dispersion. These basiccompounds may be used alone or in combination of two or more.

The amount of the basic compound to be used is 0.05 equiv or more of thecarboxyl group, carboxylic anhydride group or sulfonic group in thepolymer block (B) of the block copolymer (I), and is preferably from 0.2to 5 equiv and more preferably from 0.3 to 1.5 equiv in view of makingthe particle size of dispersed particles more finer. One equivalent ofthe basic compound per one mole of the carboxyl group or sulfonic groupcorresponds to one mole of the basic compound, whereas corresponds totwo moles of the basic compound for the carboxylic anhydride group.

These basic compounds are preferably used in the form of aqueoussolution.

The proportion of the block copolymer (I) and the aqueous solution ofthe basic compound in the aqueous dispersion (I) is preferably 95 to 30parts by weight of the aqueous solution of the basic compound based on 5to 70 parts by weight of the block copolymer (I).

The block copolymer (II) is composed of the polymer block (X) mainlyconstituted by a constitutional unit derived from an aromatic vinylcompound (hereinafter may be referred to merely as “X”) and the polymerblock (Y) constituted by a constitutional unit derived from a conjugateddiene (hereinafter may be referred to merely as “Y”). The polymer block(X) and the polymer block (Y) may be bonded in any of linearconfiguration, branched configuration, radial configuration, andcombinations thereof, with the bonding in linear configuration beingpreferred.

The block copolymer (II) may have a block structure represented by theformula:X—Y, (X—Y)_(m)—X, (X—Y)_(n), or Y—(X—Y)_(p)wherein m, n and p are each an integer of one or more. Block copolymersin which the polymer block (X) and the polymer block (Y) are linearlybonded are preferred, with diblock copolymers of the formula X—Y andtriblock copolymers of the formula X—Y—X being more preferred, andtriblock copolymers of the formula X—Y—X being still more preferred.

When the block copolymer (II) contains two or more polymer blocks (X),the structures of these polymer blocks (X) may be the same or different.Also, when the block copolymer (II) contains two or more polymer blocks(Y), the structures of these polymer blocks (Y) may be the same ordifferent. For example, two polymer blocks (X) in the triblock structureof the formula X—Y—X, or two polymer blocks (Y) in the triblockstructure of the formula Y—X—Y may be the same or different in the kindsof aromatic vinyl compound and conjugated diene, the bondingconfiguration, the number-average molecular weight, etc.

Examples of the aromatic vinyl compound for constituting the polymerblock (X) include styrene, α-methylstyrene, o-methylstyrene,m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene,2,4,6-trimethylstyrene, vinylnaphthalene, vinylanthracene,4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene,2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, t-butylstyrene, indene,acetonaphthylene, monofluorostyrene, difluorostyrene, monochlorostyreneand methoxystyrene. These may be used alone or in combination of two ormore. Preferred are styrene and α-methylstyrene.

The polymer block (X) may be composed of, in addition to theconstitutional unit derived from the aromatic vinyl compound, aconstitutional unit derived from another copolymerizable monomer, ifrequired. The content of the constitutional unit derived from anothercopolymerizable monomer is preferably 30% by weight or lower (inclusiveof zero) and more preferably 10% by weight or lower (inclusive of zero)of the weight of the polymer block (X). Examples of such anothercopolymerizable monomer include 1-butene, pentene, hexene, butadiene,2-methyl-1,3-butadiene (isoprene) and methyl vinyl ether.

Examples of the conjugated diene for constituting the polymer block (Y)include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene,1,3-pentadiene and 1,3-hexadiene. These may be use alone or incombination of two or more. Preferred are isoprene, butadiene and amixture thereof, with isoprene and a mixture of isoprene and butadienebeing more preferred. When the polymer block (Y) contains constitutionalunits derived from two or more kinds of conjugated dienes, theseconstitutional units may be bonded in any configuration of random,taper, partial block, or a combination thereof.

The polymer block (Y) may be hydrogenated. The degree of hydrogenationis preferably 50 mol % or more (inclusive of 100 mol %) and morepreferably 70 mol % or more (inclusive of 100 mol %), because theaqueous dispersion capable of forming a coating film excellent in heatresistance and weatherability is obtained.

The content of 1,2-bond and 3,4-bond in the polymer block (Y) ispreferably 30 mol % or more (inclusive of 100 mol %). When the polymerblock (Y) is an isoprene polymer block which may be hydrogenated, or anisoprene-butadiene copolymer block which may be hydrogenated, thecontent of 1,2-bond and 3,4-bond in the polymer block (Y) is morepreferably 40 mol % or more (inclusive of 100 mol %). When the polymerblock (Y) is a butadiene polymer block which may be hydrogenated, thecontent of 1,2-bond in the polymer block is more preferably 60 mol % ormore (inclusive of 100 mol %).

The content of the constitutional unit derived from the aromatic vinylcompound is preferably from 5 to 70% by weight and more preferably from10 to 60% by weight based on the weight of whole constitutional units ofthe block copolymer (II). By the use of the block copolymer (II) havinga content of the constitutional unit derived from the aromatic vinylcompound within the above range, the coating film formed from theaqueous dispersion is excellent in the balance between flexibility andstrength.

The number-average molecular weight of the polymer block (X) ispreferably from 2,500 to 100,000, and the number-average molecularweight of the polymer block (Y) is preferably from 10,000 to 200,000.The number-average molecular weight of the block copolymer (II) ispreferably from 20,000 to 300,000 and more preferably from 30,000 to150,000, although not limited thereto.

The block copolymer (II) may have a functional group such as hydroxylgroup, epoxy group, halogen atom and amino group at the molecular end orin the molecular chain, and a carboxyl group at the molecular end. Thepolymer block (Y) may have a carboxyl group or an acid anhydride group.

The block copolymer (II) is produced, for example but not limited to, bya method where the aromatic vinyl compound and the conjugated diene aresuccessively polymerized in an inert organic solvent such as n-hexaneand cyclohexane using an alkyllithium compound as a polymerizationinitiator optionally in the presence of tetrahydrofuran ortetramethylethylenediamine, and the polymerization is terminated by theaddition of an active hydrogen-containing compound such as alcohols atthe time when the the desired molecular structure and molecular weightare attained. The block copolymer thus produced is preferablyhydrogenated in an inert solvent such as n-hexane and cyclohexane at 20to 150° C. under a hydrogen pressure of 0.1 to 15 MPa in the presence ofa hydrogenation catalyst such as Ziegler catalyst made of analkylaluminum compound with cobalt, nickel, etc. Block copolymers (II)commercially available are also usable.

The method of incorporating the block copolymer (II) into the aqueousdispersion of the block copolymer (I) is not limited. The aqueousdispersion of the present invention is produced, for example, by addingan aqueous dispersion of the block copolymer (II) to an aqueousdispersion of the block copolymer (I), or by dispersing the blockcopolymer (I) simultaneously with the block copolymer (II) into anaqueous medium.

The aqueous dispersion of the block copolymer (II) is produced, forexample, by dissolving the block copolymer (II) in an organic solvent,dispersing the resultant solution in water containing a surfactant understirring, and then removing the organic solvent.

The organic solvents usable are those capable of dissolving the blockcopolymer (II). Examples thereof include aliphatic hydrocarbons such aspentane, hexane and octane; alicyclic hydrocarbons such as cyclohexane;and aromatic hydrocarbons such as benzene, toluene and xylene. These maybe used alone or in combination of two or more. Preferred are alicyclichydrocarbons and aromatic hydrocarbons, with cyclohexane, toluene andxylene being more preferred.

The surfactant may be anionic, cationic or nonionic, and selectedaccording to its purpose of use. The amount of the surfactant to be usedis usually from 0.1 to 40 parts by weight per 100 parts by weight of theblock copolymer (II), with a minimum amount required being preferred.

Examples of the anionic surfactant include salts of higher fatty acids,salts of higher secondary fatty acids, sulfuric ester salts of higherprimary alcohols, sulfuric ester salts of higher secondary alcohols,salts of higher primary alkylsulfonic acids, salts of higher secondaryalkylsulfonic acids, salts of higher alkyldisulfonic acids, salts ofsulfonated higher fatty acids, sulfuric ester salts of higher fattyacids, salts of higher fatty ester sulfonic acids, sulfuric ester saltsof higher alcohol ethers, sulfonic salts of higher alcohol ethers,alkylolsulfuric ester salts of higher fatty amides, salts ofalkylbenzensulfonic acids, salts of alkylphenolsulfonic acids, salts ofalkylnaphthalenesulfonic acids, salts of alkylbenzoimidazolesulfonicacids, salts of alkylphosphoric acids, salts of alkyletherphosphoricacids, and salts of alkylallyletherphosphoric acids.

Examples of the cationic surfactant include amine salt types andquaternary ammonium salt types.

Examples of the nonionic surfactant include polyethylene glycol nonionicsurfactants and polyhydric alcohol nonionic surfactants. Examples of thepolyethylene glycol nonionic surfactants include adducts of higheralcohols with ethyleneoxide, adducts of alkylphenols with ethyleneoxide,adducts of fatty acids with ethyleneoxide, adducts of polyhydric alcoholfatty acid esters with ethyleneoxide, adducts of higher alkylamines withethyleneoxide, adducts of fatty acid amides with ethyleneoxide, adductsof fats and oils with ethyleneoxide and adducts of polypropylene glycolwith ethyleneoxide. Examples of the polyhydric alcohol nonionicsurfactants include glycerol fatty acid esters, pentaerythritol fattyacid esters, sorbitol fatty acid esters, sorbitan fatty acid esters,sucrose fatty acid esters, polyhydric alcohol alkyl ethers and fattyacid amides of alkanolamines. These may be used alone or in combinationof two or more.

The organic solvent solution of the block copolymer (II) can bedispersed into water by using a container equipped with a mixing means.Examples of the mixing means include, but not limited to, turbine-typestirrer, colloid mill, homomixer, homogenizer and extruder because ahigh shear force is obtained. Alternatively, the dispersion may beperformed using a line mixer equipped with a movable stirrer or a linemixer equipped with a non-movable stirrer such as “Static Mixer”(tradename of Noritake Co., Ltd.).

After dispersing the organic solvent solution of the block copolymer(II) into water, the organic solvent can be azeotropically removed withwater, for example, using a reactor with a stirrer and a condenser, avented extruder, or a rotary evaporator. The removal of the organicsolvent is performed either under atmospheric pressure or under reducedpressure.

In the aqueous dispersion of the present invention, the weight ratio ofthe block copolymer (II) and the block copolymer (I) is preferably from10:90 to 90:10 and more preferably from 20:80 to 80:20.

The aqueous dispersion of the present invention may further contain acrosslinking agent. The crosslinking agent usable in the presentinvention is a water-soluble or water-dispersible compound having in onemolecule two or more functional groups reactive with the carboxyl group,acid hydride group or sulfonic group in the block copolymer (I).Examples of such functional groups include an epoxy group, an aziridinegroup, an oxazoline group, a carbodiimide group and an isocyanate group.

Preferred as the crosslinking agent are epoxy compounds, withpolyfunctional epoxy compounds having an epoxy equivalent (weight perone equivalent of epoxy group) of from 50 to 2,500 being more preferred,and polyfunctional epoxy compounds having an epoxy equivalent of from100 to 1,000 being still more preferred. The molecular weight of thepolyfunctional epoxy compounds is preferably from 150 to 5,000 and morepreferably from 200 to 3,000.

Examples of the epoxy compound include sorbitol polyglycidyl ether,sorbitan polyglycidyl ether, polyglycerol polyglycidyl ether,pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether,triglycidyl-tris(2-hydroxyethyl) isocyanurate, glycerol polyglycidylether, trimethylolpropane polyglycidyl ether, resorcin diglycidyl ether,neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether,polyethylene glycol diglycidyl ether, polypropylene glycol diglycidylether, polytetramethylene glycol diglycidyl ether, allyl glycidyl ether,2-ethylhexyl glycidyl ether, phenyl glycidyl ether,phenol(ethyleneoxide)glycidyl ether, p-t-butylphenyl glycidyl ether,lauryl alcohol(ethyleneoxide)glycidyl ether, diglycidyl adipate,glycidyl o-phthalate, hydroquinone diglycidyl ether, bisphenol Adiglycidyl ether, bisphenol S diglycidyl ether, diglycidylterephthalate, glycidylphthalimide, dibromophenyl glycidyl ether anddibromoneopentyl glycol diglycidyl ether, with ethylene glycoldiglycidyl ether, polyethylene glycol diglycidyl ether and bisphenol Adiglycidyl ether being preferred because their aqueous dispersions areeasily prepared.

These epoxy compounds are easily available in the form of aqueousdispersions, for example, commercially available as trademanes of“Denacol” and “Denacast” each from Nagase Chemicals, Ltd. and “Epolsion”from Kanebo NSC, Ltd. The aqueous solution of water-soluble epoxycompounds can be easily prepared without using commercial products.

Examples of the crosslinking agent other than the polyfunctional epoxycompounds include polyfunctional aziridine compounds such as “PZ-33”(tradename; manufactured by Nippon Shokubai Co., Ltd.); polyfunctionaloxazoline compounds such as “WS-500” and “K-2030E” (tradenames, eachmanufactured by Nippon Shokubai Co., Ltd.); polyfunctional carbodiimidecompounds such as “Carbodilite E-01” and “Carbodilite V-02” (tradenames;each manufactured by Nissinbo Industries, Inc.; and polyfunctionalisocyanate compounds such as “CR-60N” (tradename; manufactured byDainippon Ink & Chemicals, Inc., and “Takelac WD” (tradename;manufactured by Takeda Pharmaceutical Company Limited).

The amount of the crosslinking agent to be used is preferably from 0.2to 20% by weight of the total weight of the block copolymer (I) and theblock copolymer (II).

The aqueous dispersion of the present invention may also contain atackifier in an amount not adversely affecting the effects of theinvention, preferably from 0.1 to 100% by weight of the total weight ofthe block copolymer (I) and the block copolymer (II). The tackifier hasbeen widely used in the technical fields of adhesive tapes, paints, hotmelt adhesives, etc. Examples thereof include petroleum resins such asC₄-, C₅-, or C₉-petroleum resins and C₄ to C₉-copolymerized petroleumresins; saturated petroleum resins prepared by the hydrogenation of thepetroleum resins; rosin derivatives such as rosins, polymeric rosins,hydrogenated rosins, esters of rosins with glycerol or pentaerythritol,and resin acid dimers; terpene-based resins such as terpene resinspolymerized with α,β-pinene, terpene phenol resins, aromatic modifiedterpene resins and hydrogenated terpene resins; coumarone-indene resins;phenol resins; xylene resins; and styrene resins. The tackifiersgenerally have a number-average molecular weight of from 500 to 3,000and a softening point of from 50 to 140° C. Preferred are the saturatedpetroleum resins, terpene-based resins and rosin derivatives because thebonding and adhesion properties to substrates of the aqueous dispersionsare further improved in some cases. Commercially available saturatedpetroleum resins are usable, which include, for example, “Regalrez” and“Regalite” (each manufactured by Rika Hercules, Ltd.), “Arkon”(manufactured by Arakawa Chemical Industries, Ltd.), “Escorez”(manufactured by Tonex Co., Ltd.), “Quintone” (manufactured by ZeonCorporation), and “Imarv” (manufactured by Idemitsu Petrochemical Co.,Ltd.). Examples of aqueous emulsion-type tackifiers include “SuperEster” and “Tamanol” (each manufactured by Arakawa Chemical Industries,Ltd.).

Further, the aqueous dispersion may contain polyurethane or vinylpolymer. Examples of polyurethanes include (a) an aqueous dispersion ofpolyurethane resin which is produced by reacting an organicpolyisocyanate, a polymer polyol and a carboxyl-containing polyol into acarboxyl-containing, isocyanate-terminated prepolymer, and thenpolymerizing the prepolymer in the presence of a chain extender such aspolyamines simultaneously with or after the step of emulsifying theprepolymer in water by the aid of neutralization with a tertiary amine,etc.; (b) an aqueous dispersion of polyurethane resin which is producedby reacting an organic polyisocyanate and a polymer polyol into anisocyanate-terminated prepolymer, and then polymerizing the prepolymerin the presence of a chain extender such as polyamines simultaneouslywith or after the step of emulsifying the prepolymer in water by the aidof a surfactant; (c) an aqueous dispersion of polyurethane resin whichis produced by reacting an organic polyisocyanate, a polymer polyol, acarboxyl-containing polyol and a chain extender into acarboxyl-containing polyurethane, and then emulsifying the polyurethanein water by the aid of neutralization with a tertiary amine, etc.; (d)an aqueous dispersion of polyurethane composite resin which is producedby emulsion-polymerizing a vinyl monomer in the aqueous dispersion ofpolyurethane resin described in (a) to (c); and (e) an aqueous solutionor an aqueous dispersion of polyurethane resin which is produced byreacting an organic polyisocyanate, a polymer polyol including apolyoxyalkylene glycol and a chain extender into a polyoxyalkylenegroup-containing polyurethane, and then dissolving or emulsifying thepolyurethane in water. Preferred are (1) polyurethane having aneutralized carboxyl group in its backbone chain, (2) polyurethanehaving a mono- or divalent aliphatic hydrocarbon group having 50 to1,000 carbon atoms; and (3) composite resins composed of a polyurethaneresin and a polymer of vinyl monomer.

The vinyl polymers are suitably produced from compounds having in itsmolecule at least one unsaturated bond capable of radical polymerizationor radical copolymerization, for example, from one or more monomersincluding styrene monomers such as styrene, α-methylstyrene,vinyltoluene, hydroxystyrene, and p-styrenesulfonic acid inclusive ofits sodium salt and potassium salts; (meth)acrylonitrile; vinyl estermonomers such as vinyl acetate and vinyl pivalate; (meth)acrylic estermonomers such as methyl (meth)acrylate, ethyl(meth)acrylate,butyl(meth)acrylate, dodecyl (meth)acrylate, 2-ethylhexyl(meth)acrylateand 2-hydroxyethyl (meth)acrylate; (meth)acrylamide;N-vinyl-2-pyrrolidone; diene monomers such as 1,3-butadiene, isoprene,chloroprene and 1,5-hexadiene; maleic monomers such as maleic acid,diethyl maleate and di-n-butyl maleate; fumaric monomers such as fumaricacid and di-n-butyl fumarate; vinyl chloride; and vinylidene chloride.Preferred are vinyl polymers produced from styrene monomers, vinyl estermonomers and (meth)acrylic ester monomers. Also usable as the vinylpolymer include aqueous dispersions of vinyl polymers which are marketedas aqueous emulsion-type adhesives, for example, acrylic aqueousemulsion adhesives using acrylic esters as the main vinyl monomer, vinylacetate aqueous emulsion adhesives using vinyl acetate as the main vinylmonomer, and styrene aqueous emulsion adhesives using styrene as themain vinyl monomer.

The aqueous dispersion may further contain a thickening agent, adefoaming agent, etc., if required. Examples of the thickening agentinclude water-soluble polymers such as carboxymethylcellulose,methylcellulose, sodium polyphosphate, polyvinyl alcohol, sodiumpolyacrylate, casein, vinyl alcohol-methacrylic acid copolymer, starch,dextrin and proteins.

Further, in order to improve the wettability of substrates, a smallamount of an organic solvent may be added to the aqueous dispersion.Examples of the organic solvent include hydrocarbons such as pentane,hexane, octane, cyclohexane, benzene, toluene and xylene; alcohols suchas ethanol and isopropyl alcohol; esters such as ethyl acetate; ketonessuch as acetone and methyl ethyl ketone; and ethers such astetrahydrofuran and dioxane.

Further, the aqueous dispersion may also contain, if required,stabilizers such as antioxidants, weathering stabilizers, thermaldecomposition inhibitors, ultraviolet light absorbers; colorants such astitanium oxide and organic pigments; conductivity modifiers such ascarbon black and ferrite; and organic or inorganic fillers.

Examples of the antioxidants include 2,6-di-t-butyl-p-cresol,o-t-butyl-p-cresol,tetrakis-[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane,β-naphthylamine and p-phenylene diamine.

Examples of the ultraviolet light absorbers include2,4-dihydroxybenzophenone,2-(2′-dihydroxy-3′,5′-di-t-butylphenyl)-5-chlorobenzotriazole,2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole andbis(2,2′,6,6′)-tetramethyl-4-piperidine) sebacate.

Examples of the organic fillers include wood powder, pulp powder, andparticles of polymers such as rayon, vinylon, polyamides,polyamideimides, polyimides and polytetrafluoroethylene. Examples of theinorganic fillers include silicates such as talc, clay, kaolin and mica;oxides such as silica, titanium oxide, iron oxide and zinc oxide;hydroxides such as aluminum hydroxide and magnesium hydroxide;carbonates such as calcium carbonate and magnesium carbonate; andsulfates such as barium sulfate and calcium sulfate.

The concentration of the aqueous dispersion is not critical, and ispreferably controlled so as to provide a viscosity suitable forapplication to the substrates. The concentration of the block copolymer(I) and the block copolymer (II) is preferably from about 1 to about 50%by weight in total.

The aqueous dispersion is excellent in the bonding and adhesionproperties to substrates made of non-polar materials such as polyolefinresins, in particular, substrates made of polypropylene, and alsoexcellent in the bonding and adhesion properties to substrates made ofpolar materials. Therefore, the aqueous dispersion is useful as coatingmaterials such as primers for use in coating and bonding operations,paints, adhesives and surface modifiers.

For example, the aqueous dispersion is suitable as the coating materialsfor molded articles made of polyolefins such as high-pressurepolyethylene, medium-low-pressure polyethylene, polypropylene,poly-4-methylpentene and polystyrene; and polyolefin copolymers such asethylene-propylene copolymers, ethylene-butene copolymers,propylene-butene copolymers and ethylene-propylene-diene terpolymers.

The aqueous dispersion is also used for surface-treating, in addition tothe molded articles made of polyolefins or other polymers mentionedabove, molded articles made of polypropylene and a synthetic rubber,molded articles made of polyamide resin, unsaturated polyester resin,polybutylene terephthalate resin or polycarbonate resin, as well as,steel plates and electro-deposited steel plates. By forming a primercoat of the aqueous dispersion on a surface, the adhesion between thesurface and paints, adhesives, etc. each mainly made of polyurethaneresin, fatty acid-modified polyester resin, oil-free polyester resin,melamine resin or epoxy resin can be improved. The aqueous dispersion isalso used to form coating films excellent in visibility and impactstrength at low-temperatures.

Since the coating film to be formed is enhanced in flexibility, theaqueous dispersion is useful in applying, in particular, to substratesexposed to vibration or flexible substrates.

Specifically, the aqueous dispersion is suitable as a primer forimproving the adhesion of paints, adhesives, etc. to the surfaces ofmolded articles exposed to vibration, such as automotive bumpers made ofpolyolefin such as polypropylene or made of polypropylene and asynthetic rubber. The aqueous dispersion is also suitable as a primerfor improving the adhesion of paints, adhesives, etc. to surfaces ofsoft substrates or substrates to be repeatedly bent such as films,sheets and tubes each made of polyolefin, polyolefin fibers and woven ornonwoven fabrics made of polyolefin fibers.

The aqueous dispersion is applied to the surface of substrates by knownmethods, preferably by a spray coating, for example, by spaying theaqueous dispersion onto the surface of substrates with a spray gun. Theapplication to woven or nonwoven fabrics is performed by gravure coatingor dipping. The application to substrates is conducted at roomtemperature, and the applied aqueous dispersion is dried by a suitablemethod such as air drying and force-drying under heating to form coatingfilms.

After applying the aqueous dispersion to the surface of substrates andthen drying as described above, the surface of substrates may be coatedwith paints, adhesives, etc. by electrostatic painting, spray painting,brush painting, etc. The kinds of paints and adhesives are not limited.The aqueous dispersion is preferably used to form a primer on moldedarticles, which primer is highly adhesive to paints such as solvent-typethermoplastic acrylic resin paints, solvent-type thermosetting acrylicresin paints, acryl-modified alkyd resin paints, epoxy resin paints,polyurethane resin paints, and melamine resin paints. The appliedpaints, adhesives, etc. are cured by known heating methods usingnichrome wire heater, infrared heater or high-frequency heater, to forma desired coating film on substrates. The method for curing the coatingfilm depends upon materials and shapes of molded articles, properties ofpaints or adhesives used, etc.

The aqueous dispersion is also useful as coating materials(water-proofing agent, mold release agent, heat sealing aid, adhesivefor laminating different materials, ink, etc.) for articles with variousshapes, which are made of paper, wood, metal, plastics, etc., such asmolded articles, films, sheets, fibers, woven fabrics and nonwovenfabrics; modifiers for aqueous paints or aqueous inks which improvedispersion of pigments, gloss, abrasion resistance, water resistance,etc.; binders for ink-jet printing inks or color copying; modifiers fortoners; lustering agents; and surface-treating agents for metals.

EXAMPLES

The present invention will be described in more detail by reference tothe following examples, but it should be noted that these examples areonly illustrative and not intended to limit the scope of the presentinvention thereto.

In the following examples and comparative examples, properties ofcoating films produced from aqueous dispersions such as strength,elongation and adhesion properties were measured by the followingmethods.

A. Strength and Elongation

An aqueous dispersion was applied onto a sheet made of Teflon(registered trademark) and dried at room temperature for 24 h andfurther at 80° C. under reduced pressure for 24 h. The resultant coatingfilm was peeled off from the Teflon sheet, to obtain a 0.5 mm-thickfilm. The film was cut into a size of 5 mm in width and 20 mm in length,and pulled at room temperature at a rate of 50 mm/min in the length-wisedirection to measure the breaking strength and the elongation at breakusing “Autograph” (tradename) available from Shimadzu Corporation.

B. Adhesion Properties (Interlaminar Adhesion Strength)

A 1 mm-thick plate made of polypropylene (“Sun-Allomer PC412A”(tradename) manufactured by Japan Polyolefins Co., Ltd.) was washed withisopropyl alcohol, spray-coated with an aqueous dispersion in a drythickness of 10 μm, dried at 50° C. for 30 min, and then annealed at 80°C. for 15 min. After overlaying the following cover film on the formedcoating film, the plate was heated in a dryer at 120° C. for 35 min,subjected to a pressure of 0.98 MPa, and cooled to room temperatureunder the same pressure, to produce a laminate. The peel strength (g/10mm) between the polypropylene plate and the coating film prepared fromthe aqueous dispersion was measured by a 180° peel test (peeling speed:50 mm/min) at 23° C. and 65% RH using a tensile tester (“Autograph”(tradename) manufactured by Shimadzu Corporation).

-   -   Cover Film: 0.1 mm-thick film prepared by press-molding a        styrene elastomer (“Hybrar” (tradename) manufactured by Kuraray        Co., Ltd.).        C. Adhesion Properties (After Vibration)

A 1 mm-thick plate made of polypropylene (“Sun-Allomer PC412A”(tradename) manufactured by Japan Polyolefins Co., Ltd.) was washed withisopropyl alcohol, spray-coated with an aqueous dispersion in a drythickness of 10 μm, dried at 50° C. for 30 min, and then annealed at 80°C. for 15 min. A two-pack urethane topcoat paint (a blend of 10 parts byweight of “Retan PG80” (tradename) and one part by weight of “RetanCuring Agent” (tradename) manufactured by Kansai Paint Co., Ltd.) wasapplied onto the resultant coating film in a coating thickness of 50 μm,dried at 50° C. for one hour and then annealed at 100° C., to prepare apainted plate.

Next, 100 cross cuts were formed on the cured coating film of thepainted plate by cutting with a cutter at 1-mm intervals. Using anultrasonic washing machine (tradename “Bransonic 2510J-DTH” manufacturedby Branson Ultrasonic Corporation), the plate was then exposed toultrasonic waves for 3 min with the plate immersed in water. Afterremoving water on the surface of the plate, a strip of cellophaneadhesive tape was applied onto the 100 cross cuts. Then, the adhesivetape was rapidly peeled off at an angle of 90°. The number of cross cutsremained not peeled was counted to evaluate the adhesion properties. Thesame peel test was repeated while omitting the exposure to ultrasonicwaves and the number of cross cuts remained not peeled was counted.

Production Example 1

Production of Aqueous Dispersion (I-1) of Block Copolymer (I-1) Composedof Propylene-α-Olefin Copolymer Block/ethyl Acrylate-Acrylic AcidCopolymer Block

(1) Into a 1-L reactor, 500 g of a propylene-α-olefin copolymer (“TafmerXR110T” (tradename) manufactured by Mitsui Chemicals, Inc.) wasintroduced, which was then stirred for 2 h after the inner temperaturewas raised up to 390° C., to obtain a double bond-terminatedpropylene-α-olefin copolymer. The content of the terminal double bondwas 188.7 μmol/g.(2) Into a reactor, were charged 100 parts by weight of the doublebond-terminated propylene-α-olefin copolymer produced in the step (1),300 parts by weight of xylene and 4.3 parts by weight of thio-S-aceticacid. After fully replacing the inner atmosphere with nitrogen, 0.1 partby weight of 2,2′-azobisisobutyronitrile was added. The reaction wasallowed to proceed at 90° C. for 2 h, to produce a thioacetyl-terminatedpropylene-α-olefin copolymer. The content of the terminal thioacetylgroup was 179.2 μmol/g and the degree of addition was 95%.(3) Into a mixed solvent of 120 parts by weight of xylene and 30 partsby weight of n-butanol, 100 parts by weight of the thioacetyl-terminatedpropylene-α-olefin copolymer produced in the step (2) was dissolved.After adding 5.7 parts by weight of a 4% solution of sodium hydroxide inn-butanol to the solution, the reaction was allowed to proceed for onehour at the toluene refluxing temperature, to produce amercapto-terminated propylene-α-olefin copolymer. The content of theterminal mercapto group was 175.6 μmol/g, and the degree of reaction was98%.(4) Into 150 parts by weight of xylene, 100 parts by weight of themercapto-terminated propylene-α-olefin copolymer produced in the step(3) was dissolved. After adding 90 parts by weight of ethyl acrylate and10 parts by weight of acrylic acid to the solution,1,1′-azobis(cyclohexane-1-carbonitrile) was further added in a nitrogenatmosphere at 90° C. in an amount such that the rate of polymerizationwas about 10% per hour. The reaction was stopped at the time when thedegree of polymerization reached 95%. By removing the solvent in avacuum dryer, a diblock copolymer (I-1) (hereinafter referred to merelyas “block copolymer (I-1)”) composed of a propylene-α-olefin copolymerblock (A1) and an ethyl acrylate-acrylic acid copolymer block (B1)(ethyl acrylate:acrylic acid=90:10 by weight) was obtained. Thenumber-average molecular weight was 5,300 for the polymer block (A1),4,500 for the polymer block (B1), and 9,800 for the block copolymer(I-1). The melting point of the block copolymer (I-1) was 103° C.(5) In a 0.5-L reactor equipped with a stirrer and a condenser, 50 g ofthe block copolymer (I-1) was dissolved in 250 g of xylene at 100° C.Then, 300 g of a 0.1% aqueous solution of sodium hydroxide was added tothe solution from a dropping funnel over one hour, to prepare axylene-water suspension. By removing xylene in the suspension bydistillation, a crude aqueous emulsion was obtained. Into a pressurereaction vessel, 300 g of the crude aqueous emulsion (resin content: 50g) and 3.9 g of 28% ammonia water were charged, and the contents wasstirred at 160° C. for one hour. After stirring, the mixture was cooledto room temperature to obtain an aqueous dispersion (I-1). The dispersedmatter in the aqueous dispersion (I-1) was spherical, having an averageparticle size of 0.3 μm. The aqueous dispersion (I-1) was kept stablewithout change in the particle size even after allowed to stand for oneweek.

Production Example 2

roduction of Aqueous Dispersion (I-2) of Block Copolymer (I-2) Composedof Propylene-α-Olefin Copolymer Block/TetrahydrofurfurylAcrylate-Acrylic Acid Copolymer Block

Into 150 parts by weight of xylene, 100 parts by weight of themercapto-terminated propylene-α-olefin copolymer produced in the step(3) of Production Example 1 was dissolved. After adding 90 parts byweight of tetrahydrofurfuryl acrylate and 10 parts by weight of acrylicacid to the solution, 1,1′-azobis(cyclohexane-1-carbonitrile) wasfurther added in a nitrogen atmosphere at 90° C. in an amount such thatthe rate of polymerization was about 10% per hour. The reaction wasstopped at the time when the degree of polymerization reached 95%. Byremoving the solvent in a vacuum dryer, a diblock copolymer (hereinafterreferred to merely as “block copolymer (I-2)”) composed of apropylene-α-olefin copolymer block (A2) and an tetrahydrofurfurylacrylate-acrylic acid copolymer block (B2) (tetrahydrofurfurylacrylate:acrylic acid=90:10 by weight) was obtained. The number-averagemolecular weight was 5,300 for the polymer block (A2), 4,500 for thepolymer block (B2), and 9,800 for the block copolymer (I-2). The meltingpoint of the block copolymer (I-2) was 103° C.

In a 0.5-L reactor equipped with a stirrer and a condenser, 50 g of theblock copolymer (I-2) was dissolved in 250 g of xylene at 100° C. Then,300 g of a 0.1% aqueous solution of sodium hydroxide was added to thesolution through a dropping funnel over one hour, to prepare axylene-water suspension. By removing xylene in the suspension bydistillation, a crude aqueous emulsion was obtained. Into a pressurereaction vessel, 300 g of the crude aqueous emulsion (resin content: 50g) and 3.9 g of 28% ammonia water were charged, and the contents werestirred at 160° C. for one hour. After stirring, the mixture was cooledto room temperature to obtain an aqueous dispersion (I-2). The dispersedmatter in the aqueous dispersion (I-2) was spherical, having an averageparticle size of 0.3 μm. The aqueous dispersion (I-2) was kept stablewithout change in the particle size even after allowed to stand for oneweek.

Production Example 3

Production of Aqueous Dispersion (II-1) of Block Copolymer (II-1)(Hydrogenated Styrene-Isoprene-Styrene Triblock Copolymer)

(1) The polymerization was conducted in cyclohexane by successivelyintroducing styrene, isoprene and styrene into a reactor in this orderin the presence of an n-butyllithium polymerization catalyst andtetrahydrofuran, to produce a styrene-isoprene-styrene triblockcopolymer. The block copolymer thus produced was hydrogenated incyclohexane in the presence of a Ziegler hydrogenation catalyst under ahydrogen pressure of 1.96 MPa (20 kg/cm²), to produce the titledhydrogenated triblock copolymer (hereinafter referred to merely as“block copolymer (II-1)”).

The number-average molecular weight (Mn) was 120,000 for the blockcopolymer (II-1), 8,000 for each styrene block, and 104,000 for thehydrogenated polyisoprene block; the degree of hydrogenation of thehydrogenated polyisoprene block was 92%; and the content of 1,2-bond and3,4-bond in the hydrogenated polyisoprene block was 45 mol % in total,when determined by gel permeation chromatography (GPC), ¹H-NMR analysisand iodine value measurement.

(2) An aqueous dispersion was prepared from the block copolymer (II-1)according to the method described in Examples of JP 11-117180A. Namely,100 g of the block copolymer (II-1) was dissolved in 400 g ofcyclohexane. After adding 10 g of a nonionic surfactant “Nonipol 40”(tradename, polyethylene glycol-type nonionic surfactant manufactured bySanyo Chemical Industries, Ltd.) and 400 g of distilled water, thesolution was stirred with a homomixer, to prepare a uniform dispersion.The dispersion was distilled in a reaction vessel equipped with astirrer and a condenser to remove cyclohexane, to obtain an aqueousdispersion (II-1). The dispersed matter in the aqueous dispersion (II-1)was spherical, having an average particle size of 0.3 μm.

Production Example 4

Production of Aqueous Dispersion (II-2) of Block Copolymer (II-2)(Hydrogenated Styrene-Isoprene-Styrene Triblock Copolymer)

(1) The polymerization was conducted in cyclohexane by successivelyintroducing styrene, isoprene and styrene into a reactor in this orderin the presence of an n-butyllithium polymerization catalyst, to producea styrene-isoprene-styrene triblock copolymer. The block copolymer thusproduced was hydrogenated in cyclohexane in the presence of a Zieglerhydrogenation catalyst under a hydrogen pressure of 1.96 MPa (20kg/cm²), to produce the titled hydrogenated triblock copolymer(hereinafter referred to merely as “block copolymer (II-2)”).

The number-average molecular weight (Mn) was 50,000 for the blockcopolymer (II-2), 7,500 for each styrene block, and 35,000 for thehydrogenated polyisoprene block; the degree of hydrogenation of thehydrogenated polyisoprene block was 98%; and the content of 1,2-bond and3,4-bond in the hydrogenated polyisoprene block was 10 mol % in total,when determined by gel permeation chromatography (GPC), ¹H-NMR analysisand iodine value measurement.

(2) In the same manner as in the step (2) of Production Example 3 exceptfor using the block copolymer (II-2) in place of the block copolymer(II-1), an aqueous dispersion (II-2) of the block copolymer (II-2) wasprepared. The dispersed matter in the aqueous dispersion (II-2) wasspherical, having an average particle size of 0.3 μm.

Examples 1-3

An aqueous dispersion was prepared by mixing the aqueous dispersion(I-1) and the aqueous dispersion (II-1) in amounts such that the weightratio of the block copolymer (I-1) and the block copolymer (II-1) was asshown in Table 1. The coating film produced from the prepared aqueousdispersion was measured for its properties (breaking strength,elongation at break and interlaminar adhesion strength) by the methodsmentioned above. The results are shown in Table 2. Separately, a paintedplate that was produced by the method mentioned above by using theaqueous dispersion obtained in Example 2 was evaluated for its adhesionproperties (after vibration). The entire 100 cross cuts remained notpeeled in both the cases where the exposure to ultrasonic waves wasperformed for zero minute (no exposure) and for 3 min.

Examples 4-5

An aqueous dispersion was prepared by mixing the aqueous dispersion(I-1), the aqueous dispersion (II-1) and an emulsion of a tackifier(“Super Ester E-720” (tradename) manufactured by Arakawa ChemicalIndustries, Ltd.) in amounts such that the weight ratio of solidcomponents was as shown in Table 1. The coating film produced from theprepared aqueous dispersion was measured for its properties (breakingstrength and elongation at break) by the methods mentioned above. Theresults are shown in Table 3.

Example 6

An aqueous dispersion was prepared by mixing the aqueous dispersion(I-2) and the aqueous dispersion (II-1) in amounts such that the weightratio of the block copolymer (I-2) and the block copolymer (II-1) was asshown in Table 1. The coating film produced from the prepared aqueousdispersion was measured for its properties (breaking strength andelongation at break) by the methods mentioned above. The results areshown in Table 3.

Example 7

An aqueous dispersion was prepared by mixing the aqueous dispersion(I-2) and the aqueous dispersion (II-2) in amounts such that the weightratio of the block copolymer (I-2) and the block copolymer (II-2) was asshown in Table 1. The coating film produced from the prepared aqueousdispersion was measured for its properties (breaking strength andelongation at break) by the methods mentioned above. The results areshown in Table 3.

Comparative Examples 1-2

The coating film produced from only one of the aqueous dispersion (I-1)and the aqueous dispersion (I-2) was measured for its properties(breaking strength and elongation at break) by the methods mentionedabove. The results are shown in Table 3. Separately, a painted platethat was produced by the method mentioned above by using the aqueousdispersion (I-1) was evaluated for its adhesion properties (aftervibration). Although the entire 100 cross cuts remained not peeled whennot exposed to ultrasonic waves (exposed for zero minute), 50 cross cutswere peeled off when exposed to ultrasonic waves for 3 min.

TABLE 1 Ingredients of aqueous dispersion (weight parts*) blockcopolymer (I) block copolymer (II) I-1 I-2 II-1 II-2 tackifier Examples1 70 — 30 — — 2 50 — 50 — — 3 30 — 70 — — 4 66.5 — 28.5 — 5 5 21 — 49 —30 6 — 30 70 — — 7 — 30 — 70 — Comparative Examples 1 100 — — — — 2 —100 — — — *Weights of solid components in aqueous dispersion.

TABLE 2 Properties of coating film breaking interlaminar adhesionstrength elongation at break strength Examples (kg/mm²) (%) (g/10 mm) 10.18 1290 500 2 0.24 1500 300 3 0.40 1010 250

TABLE 3 Properties of coating film breaking strength elongation at break(kg/mm²) (%) Examples 4 0.16 1260 5 0.49 630 6 0.52 870 7 1.27 580Comparative Examples 1 0.14 160 2 0.17 50

Upon comparing Examples 1 to 3 with Comparative Example 1, and Examples6 and 7 with Comparative Example 2, it would appear that the aqueousdispersions containing the block copolymer (II) provide coating filmshaving an excellent flexibility.

Upon comparing the evaluation results of adhesion properties (aftervibration) of Example 2 and Comparative Example 1, it would appear thatthe aqueous dispersion containing the block copolymer (II) provides acoating film excellent in the adhesion strength to the polypropyleneplate even after the application of vibration.

Example 8

An aqueous dispersion was prepared by mixing the aqueous dispersion(I-1) and the aqueous dispersion (II-2) in amounts such that the weightratio of the block copolymer (I-1) and the block copolymer (II-2) was50/50.

The interlaminar adhesion strength of the coating film produced from theprepared aqueous dispersion was 175 g/10 mm when measured by the methoddescribed above.

Example 9

An entangled nonwoven fabric of polypropylene fibers (basis weight: 17g/m²) was impregnated with the aqueous dispersion produced in Example 1and dried, to prepare a fibrous substrate having a basis weight of 32g/m² (entangled nonwoven fabric:block copolymers (I) and (II)=53:47 byweight).

A stack of the fibrous substrates were laminated using a laminator at120° C. at a speed of 1000 mm/min to produce a laminated sheet. When thefibrous substrates were pulled toward opposite directions for peeling,the nonwoven fabrics were structurally broken.

Example 10

The aqueous dispersion produced in Example 1 was spray-coated on thesurface (not corona-treated) of a polypropylene film (“OPM-1”(tradename) manufactured by Tohcello Co., Ltd.) in a dry thickness of 25μm, dried at 50° C. for 20 min, and then annealed at 80° C. for 15 min.

An entangled nonwoven fabric of polyester fibers (basis weight: 60g/cm²) was stacked on the resultant coating film. The stack was madeinto a laminated sheet using a laminator under the conditions of 120° C.and a speed of 1000 mm/min. When the polypropylene film and the nonwovenfabric were pulled toward opposite directions for peeling, the nonwovenfabric was structurally broken.

INDUSTRIAL APPLICABILITY

In accordance with the present invention, an aqueous dispersion capableof forming a flexible coating film which is excellent in bonding andadhesion properties to various substrates is provided. The aqueousdispersion is useful as a coating material for substrates, inparticular, substrates subjected to vibration and flexible substrates.The aqueous dispersion is also applicable to substrates made of anon-polar material, in particular, substrates made mainly ofpolypropylene.

The entire content of JP 2003-44573 filed in Japan from which thisapplication claims priority is incorporated herein by reference, and thecontents of any documents including patents and patent applicationswhich are referred to herein are also incorporated by reference in theirentirety.

1. An aqueous dispersion which is produced by incorporating a blockcopolymer (II) into an aqueous dispersion (I) of a block copolymer (I)in an aqueous solution containing a basic compound, wherein: the blockcopolymer (I) is a diblock copolymer composed of a polymer block (A)mainly constituted by a constitutional unit derived from an olefinmonomer and a polymer block (B) constituted by a constitutional unitderived from a vinyl monomer (b1) having a carboxyl group, a carboxylicanhydride group or a sulfonic group and a constitutional unit derivedfrom another vinyl monomer (b2) copolymerizable with the vinyl monomer(b1); the olefin monomer comprises at least one monomer selected fromthe group consisting of ethylene, α-olefins, 2-butene, isobutylene,conjugated dienes, vinylcyclohexane and β-pinene; when the olefinmonomer comprises a conjugated diene, the polymer block (A) is a blockin which the unsaturated bonds of the constitutional units derived fromconjugated dienes are hydrogenated; a content of the basic compound is0.05 equiv or more of the carboxyl group, carboxylic anhydride group orsulfonic group contained in the unit derived from the vinyl monomer(b1); and the block copolymer (II) is composed of a polymer block (X)mainly constituted by a constitutional unit derived from an aromaticvinyl monomer and a polymer block (Y) constituted by a constitutionalunit derived from a conjugated diene monomer.
 2. The aqueous dispersionaccording to claim 1, wherein a weight ratio of the block copolymer (I)to the block copolymer (II) is from 10:90 to 90:10.
 3. The aqueousdispersion according to claim 1, wherein the polymer block (A) isderived from polyethylene, polypropylene, propyleneethylene copolymer,propylene-α-olefin copolymer or ethylene-α-olefin copolymer.
 4. Theaqueous dispersion according to claim 1, wherein the polymer block (A)has a number-average molecular weight of from 500 to 100,000, and thepolymer block (B) has a number-average molecular weight of from 500 to100,000.
 5. The aqueous dispersion according to claim 1, wherein theconstitutional unit of the polymer block (Y) comprises a unit derivedfrom isoprene, butadiene or a mixture of isoprene and butadiene.
 6. Theaqueous dispersion according to claim 1, wherein a content of 1,2-bondand 3,4-bond in the polymer block (Y) is 30 mol % or more in total. 7.The aqueous dispersion according to claim 1, further comprising atackifier.
 8. A coated substrate obtained by applying the aqueousdispersion of claim 1 to a substrate.
 9. A method of priming a surfaceof a substrate, comprising applying the aqueous dispersion of claim 1 tothe surface of the substrate.
 10. A method of adhering two substratescomprising applying the aqueous dispersion of claim 1 to a firstsubstrate; and contacting the applied dispersion with a secondsubstrate.
 11. The aqueous dispersion according to claim 2, wherein thepolymer block (A) is derived from polyethylene, polypropylene,propylene-ethylene copolymer, propylene-α-olefin copolymer orethylene-α-olefin copolymer.
 12. The aqueous dispersion according toclaim 2, wherein the polymer block (A) has a number-average molecularweight of from 500 to 100,000, and the polymer block (B) has anumber-average molecular weight of from 500 to 100,000.
 13. The aqueousdispersion according to claim 3, wherein the polymer block (A) has anumber-average molecular weight of from 500 to 100,000, and the polymerblock (B) has a number-average molecular weight of from 500 to 100,000.14. The aqueous dispersion according to claim 2, wherein theconstitutional unit of the polymer block (Y) comprises a unit derivedfrom isoprene, butadiene or a mixture of isoprene and butadiene.
 15. Theaqueous dispersion according to claim 3, wherein the constitutional unitof the polymer block (Y) comprises a unit derived from isoprene,butadiene or a mixture of isoprene and butadiene.
 16. The aqueousdispersion according to claim 4, wherein the constitutional unit of thepolymer block (Y) comprises a unit derived from isoprene, butadiene or amixture of isoprene and butadiene.
 17. The aqueous dispersion accordingto claim 2, wherein a content of 1,2-bond and 3,4-bond in the polymerblock (Y) is 30 mol % or more in total.
 18. The aqueous dispersionaccording to claim 3, wherein a content of 1,2-bond and 3,4-bond in thepolymer block (Y) is 30 mol % or more in total.
 19. The aqueousdispersion according to claim 4, wherein a content of 1,2-bond and3,4-bond in the polymer block (Y) is 30 mol % or more in total.
 20. Theaqueous dispersion according to claim 5, wherein a content of 1,2-bondand 3,4-bond in the polymer block (Y) is 30 mol % or more in total. 21.The aqueous dispersion according to claim 1, wherein the block copolymer(II) is a triblock copolymer of the formula X-Y-X, where X is thepolymer block (X) and Y is the polymer block (Y).